Telecommunications networks have traditionally been circuit-switch networks that have transmission paths dedicated to specific users for the duration of a call and that employ continuous, fixed-bandwidth transmission. Due to growth in data traffic created by the Internet and its related technologies, however, telecommunications networks are being moved to a packet-switching transmission model. Packet-switch networks provide a large range of digital services, from data to video to basic voice telephony. Packet-switch networks can allow dynamic bandwidth and may be connectionless with no dedicated path or connection-oriented with virtual circuits and dedicated bandwidth along a predetermined path.
Asynchronous transfer mode (ATM) is a connection-oriented packet-switching technology in which information is organized into small, fixed length cells. ATM carries data asynchronously, automatically assigning data cells to available time slots on demand to provide maximum throughput. Compared with other network technologies, ATM provides large increases in maximum supported bandwidth, designed-in asynchronous traffic support, support for multiple types of traffic such as data, video, and voice transmissions on shared communication lines, and virtual networking capabilities, which increase bandwidth utilization with high quality of service and ease network administration.
However, currently implemented methods for handling ATM call set-up requests are inefficient. For example, when a calling party requests a call set-up, a conventional ATM switch may fail to respond to the request before a time-out period expires. When this occurs, the calling party cannot decide how to proceed until after the time-out period, which may result in unnecessary delays in signal processing.
In addition, if the ATM switch eventually does set up a call after the time-out period has expired, the call must be torn down. Tearing down a call requires additional messages between the calling party, the ATM switch and the called party, which utilizes bandwidth and processing power resulting in decreased efficiency for the system.